#include <stdio.h>
void interchange(int *u, int *v);
int main()
{
    int x = 5, y = 10;
    printf("Originally x = %d and y = %d.\n", x, y);
    interchange(&x, &y);
    printf("Now x = %d and y = %d.\n", x, y);
}
void interchange(int *u, int *v)
{
    int temp;
    printf("Originally u = %d and v = %d.\n", *u, *v);
    temp = *u;
    *u = *v;
    *v = temp;
    printf("Originally u = %d and v = %d.\n", *u, *v);
}